Boiler-furnace.



w. M. DUNCAN.

BOILER FURNACE.

APPLICATION FILED DEC. 12. 1913- 1,179,084. Patented Apr. 11, 1916.

3 SHEETS-SHEET I.

In veil???" mam/717 W. M. DUNCAN.

BOILER FURNACE. APPLICATION FILED ,DEC. 12, 1913.

3 SHEETS-SHEET 2.

' In 2/6 72151" zZZmmMDuncan Patented Apr. 11, 1916.

W. M. DUNCAN.

B0| LER FURNACE. APPLICATION FILED DEC-12,1913.

' Patented Apr. 11, 1916.

3 SHEETS-SHEET 3.

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In van or ,1 l Z6661 .furnace. 'tion it is customary to slant or slope the fur- WILLIAM M. DUNCAN, or ALTON, rumors.

BOILER-FURNACE.

License.

Application filed December 12, 1913. Serial N 0. 806,343.

and useful Improvements in Boiler-Furnaces, of which the following is a specification.

The present invention relates to certain improvements in furnaces for boilers, and has to do with the form and arrangement of the furnace, as well as the mode or manner of its construction.

The features of invention herein disclosed are intended particularly for use in connection with water tube boilers.v However, it will presently appear that they are in no wise restricted to such use, and that although I have illustrated them as used in conjunction with a water tube boiler, still they may be used with equal facility and advantage in connection with other classes of boilers.

In previous constructions of furnace it has'been customary to provide for the grad- 1 ual expansion and burning of the gases from the timethey are formed adjacent the front end of the furnace until-they finally pass upward. into contact with the boiler tubes or flues. In such a construction the gases do not fully ignite and burn in the Furthermore, in such a construcnace roof upward away from the grate and toward the rear so that such roof does not be straight down on to the fuel bed at all points. This will insure the production of a much higher temperature in the combustion chamber than can. otherwise be obtained, with a correspondingly better fuel.

consumption and efiiciency. At the same time such constructionof the furnace roof will enable the chamber having substantially uniform cross,

Specification of Letters Patent.

fdensation of unconsumed carbon.

Patented Apr. 11, rate.

section throughout its length so that the gases will expand to their full extent. as soon as they enter such chamber and will thereafter remain in expanded condition.

Another object of the invention is to so construct the forward portion of the furnace as to provide what may be termed an ignition arch, that is a portion, of the-roof structure beneath which igniting of the fuel will commence, and wherein the distillation of the lighter volatile matters will occur.

This arrangement taken in conjunction with i the arrangement in which the gases are immedlately fully expanded in the combustion chamber, and in which the heat radiation from and to the fuel bed is direct or at right angles, will insure a thorough con-- sumption of all of the products of distillatemperature is sufficiently low to allow con- In this way a construction is produced which will burn the fuel with a total absence of smoke, orat any rate with a minimum production of smoke for any given quality of fuel.

Another object of the present invention is to so constructor arrange the aforementioned featuresthat they may be conveniently' used in conjunction with a grate of the traveling chain style, various forms of which are in familiar and constant use.

Other features of the invention relate particularly to the manner of constructing the furnace. and particularly the roof portion thereof. It is a familiar fact that the rear portion of the furnace roof generally burns away most rapidly, and therefore one of the features of my invention is to provide. 1

a construction such thatthis portion of the roof canbe conveniently reconstructed without interfering with the balance of the roof structure. v

Other features and objects will appear from a detailed description of the invention, which consists in the features of construction and combination of parts herein- .after described. and claimed.

In the drawings: Figure 1 shows a ver-- ticallongitudinal section through a furnace structure embodying. features of my invention showing afportion of a water tube boiler mounted above the same, and showing in outline a familiar type of chain grate stoker in place; Fig. 2 is a. view slmilar to rovision of a combustion that of'Fig. 1 with the exception that it-is ona larger scale and shows portlonsof the roof blocks in section to better illustrate the manner of constructing the roof; and Fig. 3 shows a vertical'cross section taken on the line 33 of Fig. 1 looking in the direction of the arrows, Fig. 3 being on an enlarged scale and the stoker being removed.

In the several figures the boiler is designated 4.- and the stoker 5. i The boiler is supported in the customary manner. Beneath the central portion of the boiler is a wall 6 having the substantially vertical lower front face 7 and the slanting upper face 8. A deflector or partition 9 directs the gases up and around the forward portions of the water tubes. The grate illustrated is a familiar'construction of stoker chain grate having the grate portion 10 which travels from the front torear and carries the fuel bed. The hopper 11 contains the fuel in the first instance, a vertically slidable door 12 controlled by the chains 13 serving to regulate the height of the opening 14 through which the fuel is carried into thefurnace by the chain. On the height of this opening depends to a large extent the thickness of the fuel bed. This construction is familiar and well known. 7

Above the forward portion of the chain grate is mounted or supported the roof 15 of a combustion chamber 16. This. roof extends rearwardlyto the point 17 somewhat in advance of the wall 6, so as to provide I the passage 18 through which the gases gain access to a space 19 before they come into contact with the boiler. In previous constructions of furnace with which. I am familiar, it has been customary to allow the.

expansion of the gases totake place gradually as they approach the chamber 19, but in the present case I have provided the combustion chamber 16 in which the gases expand at once to full volume, and in which they burn.

As illustrated particularly in Figs. 1 and 2, the roof 15 is substantially parallel to the grate, so that the aforementioned direct radiation of heat to and from the fuel bed is obtained at all points throughout the length of the fuel bed. Inasmuch as the roof of the combustion chamber is parallel to the fuel bed throughout its entire length, it necessarily follows that the gases will immediately expand to the full amount, and

complete consumption of all of the volatile matter.

Of course the fuel must be initially heated when it enters the furnace so that the distillation of gases Will commence as soon as the fuel bed enters the combustion chamber and so that ignition will commence as soon as possible. For this purpose I have provided what may be termed an ignition arch. It will be noted that the forward end of the combustion chamber is closed by means of a partition or wall 20. This wall extends down to a point somewhat above the maximum desired opening of the gate 12, so that its lower surface in effect provides an ignition arch 21 over the forward end of the fuel bed. This arch is of sufliciently high temperature to insure ignition of the fuel before the same enters the combustion chamber, and also serves to thoroughly commence the distillation of the volatile contents of the fuel at that time.

From the foregoing it will be seen that the arrangement herein disclosed is such that as rapidly as the fuel enters the furnace it is ignited, and is such that as fast as the gases are formed they expand to their full volume in the combustion chamber.

1 will now describe more in detail the construction of the roof of the combustion chamber. It was previously stated that the rear portion 17 of this roof tends to burn away most rapidly, for the reason that the gases pass around the same in their travel from the combustion chamber to the boiler. Other portions of the roof are, of course. subjected to such heat and conditions that they will in time burn away and therefore it is desirable to be able to repair or renew all portions of the roof from time to time as that may be necessary. The construction herein disclosed is such that the roof of the combustion chamber can be readily built up,

perfectly supported when once constructed, and such that replacements and repairs, particularly of the rear end 17, can be most easily effected. A number of transversely extending supporting members 22 extend across the furnace structure above the combustion chamber. As a simple and rigid form of construction, I have illustrated each of these members as composed of a pair of channels 23 placed back toback and having their ends embedded in or supported by the side walls 24 and 25 of the furnace structure. The roof proper comprises a plurality of blocks 26 of suitable form, and offire resisting material, said blocks being preferably arranged in rows from front to rear as is well illustrated in Fig. 8. Extending through the upper portions of the blocks of each row is a hollow rod 27 on which the blocks of that row are suspended or hung. Each of the rods 27 may be supported from each crosswise extending member 22 by a plate or bar 28, and as a simple means of effecting this suspension, each plate extends downwardly a sufficient distance to allow the rod to be passed through a hole in its lower end. The plates in turn are preferably set in between the. pairs of channels, and are supported on such channels by means of pins or the like 29. Those blocks 30 of the rear portion of the roof which are particularly subjected to burning are so supported that they can be readily removed from the rear ends of the rods without the necessity of disward into thespace 19. An opening 42 serves to give access to the rear portion of the furnace either for construction or repair.

From the foregoing it will be seen that I have herein disclosed a furnace arrangement and construction such that as fast as turbing the remainder of the roof construcburn away the rear end of the corresponding rod 27 may also be burned, or at any rate subjected to such aheat as to reduce or destroy its carrying or supporting power. For this reason I prefer to terminate each rod 27 somewhat forwardly of the most rearward block 30 and to insert a plug or the like 33 into the end of the rod, said plug in turn serving to support the rearmost blocks. By means of this construction the plugs can be renewed from time to time as the rearmost blocks 30 are renewed without the necessity of'disturbing any other portion of the roof structure. I

The customary form of sheet metal inclosure 34 may be built up over the roof structure if desired, for the purpose of givin a finished appearance to the furnace. It will be seen that the furnace roof extends somedistance to the rearward ofthe front end of the boiler. By carrying the roof rearward in this manner the front and rear inclosures orwalls of the space 19 may be made to diverge from each other as best illustrated in Fig. 1, so that the volume or cross sectional area of said space increases in sizeas it proceeds upwardly. As a simple.

means of effecting this construction a crosswise extending member 35 may be provided for supporting the front wall 36, a crosswise extending member 37 serving to support the slanting portion 38 of the front wall.

If desired, a sight hole 39 may be provided for inspecting the operation of the forward portion of the combustion chamber, a sight hole 40 for inspecting the operation of the ignition arch, and a sight hole 41 for inspecting the operation of that portion of the furnace wherein the gases pass upthe gases form they immediately expand into a chamber of considerable size and volume, and whichchamber is of substantially uniform size or cross-section throughout its length from front to rear. It will also be seen that I have associated with such chamber another portion wherein the fuel is originally ignited and wherein the distillation of the volatile matters commences. It will also be seen that there is a peculiar relationship or combination between the combustion chamber and the grate for the reason that at the same time that I provide a combustion chamber of uniform size or cross-section I obtain a construction in which the roof of the combustion chamber is parallel to the grate orfuel bed at all points so as to give theaforementioned advantages of direct right angled radiation.

' I do not limit myself to the particular I arrangements and construction herein illustrated and described, except as I may doin the claim, but I include within the scope of my invention any equivalent arrangements or constructions operating or capable of operating in equivalent manners to produce equivalent results.

I claim:

In a boiler furnace, the combination with I the grate, of a rear wall extending upwardly adjacent to the rear end of the grate, the upper portion of the front face of said wall slanting rearwardly up to the boiler, a combustion chamber over the forward portion .of the grate, saidchamber having a substantially fiat roof extending rearwardly to a point close to the rear wall, another wall extending upwardly from the roof of the combustion chamber and sloping forwardly into contact with the front end of the boiler, and a wall closing the upper portion 'of the front end of the combustion chamber, the roof of the combustion chamber lying substantially parallel with the grate, whereby'there is provided over the front portion of the grate a combustion chamber of substantially uniform cross section communicating in its rear portion with an expansion chamber of larger horizontal section in its upper portion than in its lower portion, substantially as described.

W. M; DUNCAN.

Witnesses:

LEO F. BERNER, .A. R. CROSSMAN. 

